SAO PAULO, Brazil (Reuters) - The second American in a month was arrested while entering Brazil for making an obscene gesture while being photographed by an immigration official, police said on Saturday.

Federal police in Foz do Iguacu on Brazil's border with Argentina and Paraguay said retired U.S. banker Douglas Allan Skolnick, 56, was jailed overnight for flipping his middle finger in a photo now required to be taken of all U.S. tourists entering Brazil.

Brazil began fingerprinting and photographing Americans entering the country in January after the U.S. government imposed a similar process on foreigners, except for those from 27 mostly European countries.

"Mr. Skolnick went before the judge this morning and opted to take the public prosecutor's offer that he pay a 15,000 real fine ($5,000) to avoid prosecution," said officer Marcos Koren of the Foz do Iguacu federal police.

Skolnick, who came into Brazil on a charter flight with 91 other tourists -- mostly American -- from Chile on Friday, is being held in his hotel room under police guard until he pays the fine, said Koren. He will then be free to leave Brazil.

Skolnick declined to comment.

On Jan. 14, an American Airlines pilot was arrested upon entry into Brazil via Sao Paulo, after flipping his finger in a photo. American Airlines paid a fine nearly $13,000 to free the pilot.